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An anonymous reader writes: National Geographic has a detailed article about efforts underway to search for life in the oceans of Europa, which are buried beneath miles of ice. A first mission would have a spacecraft orbit just 16 miles over the moon's surface, analyzing the material ejected from the moon, measuring salinity, and sniffing out its chemical makeup. A later mission would then deploy a rover. But unlike the rovers we've built so far, this one would be designed to go underwater and navigate using the bottom surface of the ice over the oceans. An early design was just tested successfully underneath the ice in Alaska. "[It] crawls along under a foot of ice, its built-in buoyancy keeping it firmly pressed against the frozen subsurface, sensors measuring the temperature, salinity, pH, and other characteristics of the water."

Astronomers and astrobiologists are hopeful that these missions will provide definitive evidence of life on other worlds. "Europa certainly seems to have the basic ingredients for life. Liquid water is abundant, and the ocean floor may also have hydrothermal vents, similar to Earth's, that could provide nutrients for any life that might exist there. Up at the surface, comets periodically crash into Europa, depositing organic chemicals that might also serve as the building blocks of life. Particles from Jupiter's radiation belts split apart the hydrogen and oxygen that makes up the ice, forming a whole suite of molecules that living organisms could use to metabolize chemical nutrients from the vents."

How do they plan to send communications back to earth from under the ice? I assume they will have a rover on the surface that will communicate with the diver and possibly a satellite, that will communicate with us.

I was wondering the same thing (about communications). Depending on how many miles of ice we're talking about would determine if any form of tethered array could be used (i.e. - "diver" drills / melts into ice for 1 or 2 miles, leaving along a cord which is connected to an uplink sat system which communicates to whatever it floating in orbit, etc.) Not sure what kind of materials we have that could ensure that the cord wouldn't break but I would think that even 2 miles worth of cord would be an awful lot to

The predominant theory at present is that it's somewhere in the ballpark of 20km. Some argue for only a few kilometers, but that's a minority view. And it's even worse when you're at the bottom, the sea is expected to be about 100km deep.

How do you communicate through 20km of ice plus up to 100km of water?The total absorption in question here is just massive. Earthquake-strength sonar? ELF waves with a dozens-of-kilometers-long antenna? Cycling your nuclear reactor on and off and having a super-sensitive n

100km of water is nothing for SONAR, especially since Europa probably lacks a lot of noise pollution sources that exist in earths oceans. Getting equipment and a power source capable of putting out enough dB would be difficult though. Also, that 20km of Ice would likely act as a mirror and just reflect any transmissions back downward. ELF SONAR as you mentioned might actually get through the ice, but probably with a large loss in signal strength.

"When we speak of the Europa mission at our shop we are talking about going for the gold ring: landing on the surface of Europa; sending a nuclear-powered cryobot carrier vehicle through the ice crust; discharging a nuclear-powered 'fast mover' autonomous underwater carrier vehicle that has planet-scale range, and selectively launching a series of miniaturized, highly intelligent AUVs [Autonomous Underwater Vehicles] to go into the more dangerous areas (e.g. around

“where there is a significant chance that contamination carried by a spacecraft could jeopardize future exploration.” We define “significant chance” as “the presence of niches (places where terrestrial microorganisms could proliferate) and the likelihood of transfer to those places."

The Europa probe is likely to get a little less scrubbing, significantly less than an Europan orbiter, but more than the Juno spacecraft [nasa.gov], as, although it will be in a Jovian orbit going near Europa, it can be placed in a "safe" orbit away from Europa at the end of the mission. But, Europa orbiters and landers will get the full treatment.

By the way, even if Mars landers had some bugs, they were sterilized, which undoubtedly greatly reduced the total bio-loading, Just because you didn't wash your hands once before dinner doesn't mean you should stop washing them altogether subsequently.

I was not aware that the bible had anything whatsoever to say about life elsewhere in the universe - in fact I seem to recall that it has nothing much to say about anything else in the universe even existing. Almost as though it was written for (or by) humans who had no knowledge of, or use for, anything not directly related to their home planet.

A first mission would have a spacecraft orbit just 16 miles over the moon's surface, analyzing the material ejected from the moon, measuring salinity, and sniffing out its chemical makeup.

Actually, the first mission dedicated to Europa will be the Europa clipper [nasa.gov], focused on Europa, but not in Europa orbit. The radiation near Europa is so intense (even for machines) that dipping in and out of the field in an inclined Jovian orbit will save about a billion dollars over going into a Europan orbit.

ok, so if we're pretty sure there's no "intelligent" life capable of nuking us...

How about we just send a reactor there... land it on the ice, and let it do its thing until it melts its way through? Is it possible to have a controlled reaction long enough to get through the ice... the spread the fissile material out in some way and have it seal itself tight for the next 10k years?

Once through, the reactor should provide plenty of power to get a signal through the ice I would think. Also, the radiation from

It is incredibly simple to drill through the ice. Bring a long a one pound sphere of depleted uranium. Before you start breaking for obit, release the sphere on an impact trajectory. Without a thick atmosphere to ablate it, I feel fairly confident in saying that the crater will be fairly deep. Repeat as needed. If you want real precision, I'm sure you can get the military to give you one of the cheap laser guidance packs they slap on dumb munitions. Rememeber that the goal here is to get through the ice, n

Yes, it is further away, intense radiation (except under the ice), more difficult but then Mars used to be like that (in some ways still is). But rather sending another rover to Mars with more evidence of water used to be there, bla-bla, etc. Cynthia Phillips of SETI said, "when looking for life, go where the water is." And there is lots more water there than on Mars but we don't know much of what is under all that ice. Mars has interesting geological features (forget sending people there, it's a bridge too far and we can't even send people to the moon). But just imagine a submarine taking pictures and video of the little fishies in the Europa oceans. Don't know if there is any there but that first mission under the ice will be very interesting.

I wonder if the ice/water transition may be miles of slush, rather than being clearly defined. If so the design in TFA isn't going to work as there will be no ceiling to use as a reference. They'll need to use temperature, sonar, or pressure readings to determine its elevation/depth, all of which will be unknown without sending something else down there first.

Well, think of how water freezes on a cold lake. There's a sharp divide because water isn't still. Heat being generated at the core of the moon would ensure warmer fluid would move towards the ice barrier, and colder fluid would move towards the core. This cycle tends to keep 'slush' from forming.

Interesting...didn't think about that. I suppose what got me thinking of the slush idea was the sheer scale of the environment compared to ours here; the entire moon is frozen. Here's some info on theories about Europa's oceans: http://en.wikipedia.org/wiki/E... [wikipedia.org]

And possibly evidence of slush, depending on how you interpret the word "ductile":

...it is predicted that the outer crust of solid ice is approximately 10–30 km (6–19 mi) thick, including a ductile "warm ice" layer...